MINOR: trace: prepend the function name for developer level traces
Working on adding traces to mux-h2 revealed that the function names are
manually copied a lot in developer traces. The reason is that they are
not preprocessor macros and as such cannot be concatenated. Let's
slightly adjust the trace() function call to take a function name just
after the file:line argument. This argument is only added for the
TRACE_DEVEL and 3 new TRACE_ENTER, TRACE_LEAVE, and TRACE_POINT macros
and left NULL for others. This way the function name is only reported
for traces aimed at the developers. The pretty-print callback was also
extended to benefit from this. This will also significantly shrink the
data segment as the "entering" and "leaving" strings will now be merged.
One technical point worth mentioning is that the function name is *not*
passed as an ist to the inline function because it's not considered as
a builtin constant by the compiler, and would lead to strlen() being
run on it from all call places before calling the inline function. Thus
instead we pass the const char * (that the compiler knows where to find)
and it's the __trace() function that converts it to an ist for internal
consumption and for the pretty-print callback. Doing this avoids losing
5-10% peak performance.
diff --git a/include/types/trace.h b/include/types/trace.h
index 03eb7db..91a57f8 100644
--- a/include/types/trace.h
+++ b/include/types/trace.h
@@ -124,7 +124,8 @@
const struct trace_event *known_events;
struct list source_link; // element in list of known trace sources
void (*default_cb)(enum trace_level level, uint64_t mask,
- const struct trace_source *src, const struct ist where,
+ const struct trace_source *src,
+ const struct ist where, const struct ist func,
const void *a1, const void *a2, const void *a3, const void *a4);
uint32_t arg_def; // argument definitions (sum of TRC_ARG{1..4}_*)
const struct name_desc *lockon_args; // must be 4 entries if not NULL